Oestrogen is a hormone produced in the ovaries. It helps control how cells grow and what they do in the body. Some cells in the breast carry receptors for oestrogen and are more dependent on the hormone to know when to grow. If breast cancer starts as one of these cells with oestrogen receptors (ER), it is classified as ER-positive (ER+), otherwise they are ER-negative. ER-positive breast cancers make up around 70% of all breast cancers.
Breast cancer – everything you need to know
1st June 2022
Breast cancer is the most common cancer in the world. We all have breast tissue so it can affect anybody, but it is much more common in women. Thanks to research, more people are surviving breast cancer every year, but it’s important to catch it early. What are the symptoms of breast cancer? What are the different types of breast cancer? Are all breast lumps cancer? How do you treat it? And what are we doing to start new cancer cures for breast cancer?
What is breast cancer?
Breast cancer is a type of cancer that happens when cells in breast tissue start to grow out of control. It is the most common type of cancer found in people born female, with 1 in 7 in the UK diagnosed with breast cancer in their lifetime. When breast cancer goes unnoticed, it often spreads to nearby lymph nodes (such as in the armpit), but can also spread to the bones, lungs, liver, and brain.
Over 2.2 million people worldwide were diagnosed with breast cancer in 2020
Almost 700,000 people worldwide died of breast cancer in 2020
What types of breast cancer are there?
Most breast cancers are carcinomas, which start in the cells that line organs and tissue in the body. Breast cancer is usually a specific type of carcinoma called an adenocarcinoma, which starts in the milk ducts or glands in the breast that make milk.
Breast cancers can also be categorised by whether it has spread to other parts of the body or not. A pre-cancer that starts in a milk duct, but hasn’t grown into other breast tissue, is called ductal carcinoma in situ (DCIS).
If it has spread into nearby breast tissue, it is called an invasive or infiltrating breast cancer. Breast cancer that has spread further, to other parts of the body, is called metastatic breast cancer. Cancer found in another part of the body that has spread from the breast is a secondary breast cancer.
Hormones and breast cancer
Thanks to research, we now know that most breast tumours are influenced by certain hormones and proteins in the body that encourage it to grow. These include oestrogen and progesterone, which are hormones that are essential in the normal function of the body. More specifically, they play important roles during puberty, the reproductive system, and the menstrual cycle. Breast cancer is often categorised depending on whether the cancer cells carry (or carry too much of) a specific receptor for that hormone or protein.
What types of breast cancer are there?
Progesterone is also produced in the ovaries and helps control how cells grow and what they do. If breast cancer cells carry progesterone receptors (PR), the breast cancer is classified as PR-positive (PR+), otherwise they are PR-negative.
Human epidermal growth hormone receptor 2 (HER2) is a normal part of the way cells communicate and signal cells to grow, however sometimes breast cancer cells can carry more HER2 than normal. If this is the case, the breast cancer is classified as HER2-positive (HER2+), otherwise it is HER2-negative. HER2+ breast cancers make up 15-20% of all cases.
If the breast cancer cells do not fall into any of these categories, it is called triple-negative breast cancer, meaning it is ER-negative, PR-negative, and HER2-negative. Most breast cancer treatments target one or more of these different receptors, so triple negative breast cancer can be more difficult to treat.
Other, less common, types of breast cancer include:
- Inflammatory breast cancer
- Paget disease of the breast
- Phllodes tumour
What causes breast cancer?
Anyone with breast tissue can be diagnosed with breast cancer. It is much more common in females, but it can also occur in males. As with all cancers, your risk of developing breast cancer increases with age, and most cases occur in people over the age of 50.
Some people have a higher risk of developing breast cancer because they have inherited a faulty gene. People with a BRCA1 or BRCA2 gene mutation are at higher risk of developing many types of cancer because both these genes are involved in the repair of damaged DNA. This can make cancer more likely because any defects in the DNA of a cell do not get fixed, and these defects can build up over time as more appear without being repaired. The more defects build up, the more likely the cell becomes cancerous.
Other risk factors include:
- A previous diagnosis with breast cancer, or a benign (non-cancerous) lump
- Previous treatment with radiotherapy
- Being overweight or obese
- Lack of physical activity
- Drinking alcohol
- Having your first period early in life and/or having periods later into life. This is believed to be because of longer exposure to the hormone oestrogen.
- Taking hormone replacement therapy (HRT). Combined HRT (oestrogen and progesterone) has a higher risk than oestrogen-only HRT.
- Taking hormonal contraceptive pills (though this is a very small increase in risk, and it decreases your risk of other cancers like ovarian cancer).
Managing your risk of breast cancer
Maintaining a healthy weight, balanced diet, reducing your alcohol intake, and getting enough exercise are all important ways to reduce your risk of breast cancer and almost all other types of cancer.
The hormones oestrogen, progesterone, and testosterone are all known to affect the risk of breast cancer. Longer exposure to these hormones over your life can increase your risk, and using HRT to manage the symptoms of menopause can come with an increased risk of breast cancer. As most cases of breast cancer occur in people over the age of 50, it is important to talk to your doctor about managing this risk.
People who are at high risk of breast cancer, such as due to an inherited faulty gene, may be prescribed medicine to reduce that risk. Patients are prescribed different medicines depending on if they are pre- or post-menopausal.. Some people at higher risk may decide to have a mastectomy, where breast tissue is removed, which substantially (but not completely) lowers the risk.
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What are the symptoms of breast cancer?
Thanks to cancer research, breast cancer can often be treated effectively if spotted early on. That’s why it’s important to recognise the signs and symptoms.
The first noticeable symptom is usually a lump in the breast, or an area of thickened breast tissue. Not all lumps are cancerous, however you should speak to your GP if you find a lump or you spot an unusual change in your breast.
Other symptoms can include:
- A change in the size or shape of one or both breasts
- Discharge from the nipples (may be streaked with blood)
- A lump or swelling in the armpit
- Dimpling on the skin of the breast
- A rash on or around the nipple
- A change in appearance of the nipple
How do you treat breast cancer?
Despite being increasingly common, survival rates for breast cancer are improving every year. In the UK, 85% of women diagnosed with breast cancer survive beyond 5 years, and 76% beyond 10 years. This is thanks to better public understanding of the symptoms, improved diagnostic tools and newer treatments that can target the cancer more effectively.
How do you treat breast cancer?
Surgery is often the first treatment, if breast cancer is caught early enough and hasn’t spread. This can be breast-conserving, where just the affected tissue and some of the surrounding healthy tissue is removed, or a mastectomy, where the entire breast or both breasts are removed.
To give patients the best chance at a cure, surgery is often paired with another treatment that aims to shrink the size of the tumour or reduce the risk of the cancer returning. This can include radiotherapy, chemotherapy, hormonal therapy, or other targeted therapies. The type of treatment and specific combination recommended to a patient depends on the type of breast cancer they have and whether it has already spread.
Controlled doses of radiation are used to kill cancer cells. This is usually used after surgery to kill any remaining cancer cells, however radiotherapy may not be the best option for all patients. This depends on the type of cancer they have and whether it has spread.
A type of medicine that kills cancer cells. There are many different chemotherapy drugs, and they are often used in combinations of two or three at once. The specific drugs used vary depending on the type of cancer and whether it has spread.
Some breast cancers are stimulated to grow by hormones already in the body, such as oestrogen, progesterone, or if the cancer cells have too many HER2 receptors. This means it is possible to use medicines that block those receptors, stopping the signals to grow. For example, tamoxifen is commonly used to treat ER-positive breast cancers as it stops oestrogen binding to the cells.
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